Coverage Declarations does not honor output split cfuncs

Changed V3EmitC to call a predefined function for initializing coverage and moved that function creation to the same place as where the variable resets are being created. This makes it possible to compile large projects (w/ heavy inlining) with coverage. (Without this patch the C++ would never finish due to the ::configure() method being way too large)

My only change was going to be to rename the visitor to the new standard, then realized the name just seemed too long to me (V3CConstructorsVisitor). I'm not really in love with how I renamed the file to make it feel better either (V3CCtors) but it'll do.